1. Field of the Invention
The present invention relates to a paint composition for heat releasing products.
2. Discussion of the Background
In order to treat injurious substances such as injurious gases contained in exhaust gas discharged from an engine, a catalyst converter is installed in an exhaust gas passage in an exhaust pipe.
In order to improve purifying efficiency for injurious substances by such a catalyst converter, it is necessary to maintain the temperature of exhaust gas and the temperature of the exhaust pipe and the like through which the exhaust gas is allowed to flow, at temperatures suitable for activating the catalyst (hereinafter, referred to also as catalyst activating temperatures).
However, during high-speed driving of the engine, the exhaust gas temporarily has such a high temperature as to exceed 1000° C. Therefore, the temperature of the exhaust gas sometimes becomes higher than the upper limit of the catalyst activating temperature range. As a result, problems are raised in that it becomes difficult to efficiently purify exhaust gas and in that the catalyst deteriorates.
For this reason, an exhaust pipe to be connected to an automobile engine needs to be capable of externally radiating heat of the exhaust gas that flows through the exhaust pipe, during high-speed driving of the automobile engine.
JP-A 2009-133213 and JP-A 2009-133214 have disclosed an exhaust pipe having a structure in which a layer composed of a crystalline inorganic material and an amorphous inorganic material is formed on a surface of a cylindrical base material made of a metal.
Specifically, JP-A2009-133213 has disclosed an exhaust pipe having an excellent heat releasing characteristic in which the layer composed of a crystalline inorganic material and an amorphous inorganic material has an infrared-ray emissivity higher than the infrared-ray emissivity of the base material.
JP-A 2009-133214 has disclosed an exhaust pipe having an excellent heat releasing characteristic in which the amorphous inorganic material located on the outer circumferential side from the crystalline inorganic material has an average thickness of 20 μm or less.
The contents of JP-A 2009-133213 and JP-A 2009-133214 are incorporated herein by reference in their entirety.